Development on a technology for acquiring a desired signal from an input signal in which the desired signal and noise are mixed has progressed. For instance, PTL 1 discloses a configuration, in which temporary estimated speech is obtained by suppressing noise included in an input speech signal, and the temporary estimated speech is corrected with use of a standard pattern of speech for making it possible to remove a noise component with high accuracy without lacking speech information. The technology of PTL 1 uses an expectation of temporary estimated speech, which is obtained by an expectation calculation processing using probabilities at which probability distributions constituting a standard pattern output temporary estimated speech, and using a mean of the probability distributions constituting the standard pattern, as a correction value of temporary estimated speech.
Note that PTL 2 and NPL 1 are described in example embodiments to be described later. PTL 2 discloses a method for removing noise. The noise removing method includes obtaining a first signal-to-noise ratio for each frequency first, obtaining a weight for each frequency based on the first signal-to-noise ratio, and obtaining estimated noise for each frequency based on a weighted frequency domain signal, which is obtained by applying a weight for each frequency to a frequency domain signal. The noise removing method further includes obtaining a second signal-to-noise ratio based on a frequency domain signal and estimated noise for each frequency, determining a suppression coefficient based on the second signal-to-noise ratio, and applying the suppression coefficient as a weight to the frequency domain signal.